Performance of PCR‐based syndromic testing compared to bacterial culture in patients with suspected pneumonia applying microscopy for quality assessment

Abstract

Performance of PCR-based syndromic testing compared to bacterial culture in patients with suspected pneumonia applying microscopy for quality assessment. APMIS. 20222022; 130: 417-426. Syndromic testing for lower respiratory tract infections with BioFireÒ FilmArrayÒ Pneumonia Panel Plus (BF) detects 27 pathogens with a turn-around-time of one hour. We compared the performance of BF with culture. Samples from 298 hospitalized patients with suspected pneumonia routinely sent for culture were also analyzed using BF. Retrospectively, patients were clinically categorized as having "pneumonia" or "no pneumonia." BF and culture were compared by analytical performance, which was evaluated by pathogen concordance, and by clinical performance by comparing pathogen detections in patients with and without pneumonia. The BF results for viruses and atypical bacteria were not included in the performance analysis. In 298 patient samples, BF and culture detected 285 and 142 potential pathogens, respectively. Positive percent agreement (PPA) was 88% (125/142). In patients with community-acquired pneumonia (CAP), clinical sensitivity was 70% and 51%, and specificity was 43% and 71% for BF and culture, respectively. In patients with hospital-acquired pneumonia, the corresponding numbers were 55% and 23%, and 47% and 68%. There was no significant improvement of performance, when only high-quality sputum samples were considered. Efficacy of both BF and culture was low. Both tests are best used in CAP patients for whom the diagnosis has already been clinically established. Indiscriminate use may be clinically misleading and a cause of improper use of antibiotics.

Diagnostic stewardship: what impacts antibiotics use?

“…The authors plan a follow-up randomized controlled trial to assess the impact of syndromic PCR on antibiotics prescribing for CAP [25]. However, Andrews et al [26] found, in a prospective analysis of 322 specimens from adults suspected of pneumonia, that the multiplex PCR panel had a 70% sensitivity and 43% specificity for CAP. Low specificity represents detection of pathogens in patient specimens who did not have clinical pneumonia, and 53 out of 129 (41%) patients who did not have clinical pneumonia received antibiotics, indicating that test ordering is a potential target for diagnostic stewardship [26].…”